Recently, liquid crystal apparatuses employing a liquid crystal panel are used in various manufactured products such as, for example, flat screen televisions, mobile telephones, tablet terminals, and liquid crystal shutters. Although this liquid crystal panel employing a liquid crystal apparatus typically uses a nematic liquid crystal, the response speed is several msec or greater and this slow response speed often poses problems. In particular, when a liquid crystal panel is used as an optical shutter in, for example, a laser projector, high-speed response is required and commonly known liquid crystal panels (hereinafter, ferroelectric liquid crystal panel) use ferroelectric liquid crystal as a liquid crystal material that satisfies this requirement.
[Description of Ferroelectric Liquid Crystal Display Panel: FIG. 10]
Here, although common knowledge, an overview of the behavior of ferroelectric liquid crystal and architecture of a ferroelectric liquid crystal panel capable of high-speed response will be described to aid in the understanding of the present invention. While ferroelectric liquid crystals include materials that have memory properties and materials that have no memory properties, the liquid crystal panel of the liquid crystal apparatus described here is taken as an example of architecture using a material of ferroelectric liquid crystal having no memory properties.
A structure of a liquid crystal panel that employs ferroelectric liquid crystal will be described with reference to FIG. 10. In FIG. 10, (a) is a plan view schematically depicting configuration of polarizing film arrangement of a ferroelectric liquid crystal panel. As in (a) of FIG. 10, in a liquid crystal panel 100, a ferroelectric liquid crystal layer 102 (encompassed by broken line) is disposed in which, between polarizing films 101a, 101b according to crossed nicols, any one among a polarization axis C of the polarizing film 101a and a polarization axis D of the polarizing film 101b and, the molecular long axis direction during a first state (arrow E) or the molecular long axis during a second state (arrow F) of liquid crystal molecules are substantially parallel.
Here, in (a) of FIG. 10, the polarization axis C of the polarizing film 101a and the molecular long axis direction during the first state (arrow E) are arranged to be substantially parallel. Although transition between the first state and the second state of the molecular long axis direction of the ferroelectric liquid crystal occurs by an application of a given voltage to the ferroelectric liquid crystal, the angular difference (i.e., the angle between arrows E and F) of the molecular long axis direction during the first state and during the second state is defined as a switching angle θ. When the switching angle θ is 45 degrees, the contrast ratio of transmission and non-transmission is the greatest and therefore, a 45-degree switching angle θ is ideal for a ferroelectric liquid crystal panel.
In FIG. 10, (b) is a cross sectional view schematically depicting the structure of the liquid crystal panel 100. In (b) of FIG. 10, the liquid crystal panel 100 includes a pair of glass substrates 103a, 103b that hold therebetween the ferroelectric liquid crystal layer 102, which has the two states. Further, the glass substrates 103a and 103b are fixed by a sealing material 106. In opposing surfaces of the glass substrates 103a, 103b, plural scanning electrodes 104 and a signal electrode 105 are provided as a driving electrode that is a transparent electrode and on top of this, oriented films 107a, 107b are provided. Lt represents light transmitted by the liquid crystal panel 100.
On the outer side of the glass substrate 103a, as described above, the first polarizing film 101a is provided such that the molecular long axis direction of the first or the second state of the ferroelectric liquid crystal layer 102 is parallel; and on the outer side of the glass substrate 103b, the second polarizing film 101b is provided such that there is a 90 degree difference with the polarization axis of the first polarizing film 101a. 
Operation of the liquid crystal panel 100 using ferroelectric liquid crystal will be described. When driving voltage VD applied to the liquid crystal panel 100 varies, optical transmissivity L of the light Lt (refer to (b) of FIG. 10) transmitted by the liquid crystal panel 100 varies. Here, switching of the ferroelectric liquid crystal, i.e., transition from one state to the other, occurs only when driving voltage of a value that is a cumulative value of a pulse width value and a pulse height value of the driving voltage VD, greater than or equal to a threshold is applied to the ferroelectric liquid crystal. Any one among the first state (non-transmission: black display) and the second state (transmission: white display) is selected for the liquid crystal panel 100 by the difference of polarity of the driving voltage VD.
The optical transmissivity L ratio of the first state (non-transmission: black display) and the second state (transmission: white display) is the contrast ratio described above, and the greatest contrast ratio is when the switching angle θ of the molecular long axis direction is 45 degrees.
Thus, when driving voltage greater than or equal to the threshold of the ferroelectric liquid crystal is applied, the second state is selected for the liquid crystal panel 100 and when driving voltage greater than or equal to the threshold of the reverse polarity of the ferroelectric liquid crystal is applied, the first state is selected.
As a result, as depicted in (a) of FIG. 10, with disposal of the polarizing films 101a, 101b, white display (transmission state) by the second state and black display (non-transmission state) by the first state is achieved. Black display (non-transmission state) by the second state and white display (transmission state) by the first state can be achieved by changing the arrangement of the polarizing films 101a, 101b. 
Thus, a liquid crystal panel that uses ferroelectric liquid crystal can select between the non-transmission state and the transmission state (the two states that switch the long axis direction of the liquid crystal molecule), switching the polarity of the driving voltage VD between positive and negative. The speed of transition between these two states (i.e., response speed) is a high speed of a few tens of μsec to a few hundred μsec and thus, is suitable for liquid crystal panels that require a high-speed response and ferroelectric liquid crystal panels are used in display elements, liquid crystal shutters, etc. (for example, refer to Patent Document 1 below).
In Patent Document 1, a ferroelectric liquid crystal element is disclosed in which, in a first frame, a positive voltage pulse is applied during a first interval, which is a given period, and a positive voltage pulse that is smaller than the voltage pulse of the first interval is applied during a second interval that is a period longer than the first interval; and in a second frame, a negative voltage pulse is applied during the first interval that is a given period, and a negative voltage pulse that is smaller than the voltage pulse of the first interval is applied during the second interval that is a period longer than the first interval, the ferroelectric liquid crystal element adjusting the intensity of transmitted light to realize a high contrast ratio by changing the value of the applied voltage of the second interval of the first frame.
Patent Document 1: Japanese Patent No. 2665331 (page 3, FIG. 4)